The invention relates to a casting nozzle for a horizontal strip casting facility, in particular for casting steel strip. Such casting facilities require liquid steel to be applied upon a cooled continuous belt from the nozzle which forms a casting channel.
Such a casting nozzle is known from “Direct Strip Casting” (DSC)—an Option for the Production of New Steel Grades”—steel research 74 (2003) No. 11/12 p. 724-731.
In this known arrangement, liquid steel flows from a distributor via a horizontally aligned feed channel into the casting nozzle which has a rectangular channel in cross section surrounded by refractory material. The casting nozzle is configured as a rectangular hollow block which is made from refractory material. Arranged in the outlet region of the casting nozzle is a so-called upper weir at the top element and a so-called lower weir at the bottom element. Both weirs interact together to form a siphon to keep back slurry residue left in the melt.
DE 196 36 697 C1 discloses a casting nozzle for thin strip casting facilities, having a backup dam which is placed upon a carrier movable in conveying direction for the thin strip, and a front dam which delimits the casting gap towards the carrier in conveying direction. According to a preferred embodiment, several outlet openings for the melt are provided in side-by-side relationship in direction of the width of the thin strip between back dam and front dam.
In this way, a more uniform distribution of the melt over the width of the casting gap should be realized. The formation of outlet openings should be realized through respective configuration of the back dam or front dam. No details are given in this regard.
For economic reasons, it is desirable to cast broadest possible steel strips. When the casting width is, e.g. >300 mm, most different problems are encountered during operation of the casting nozzle.
On one hand, this relates to the static strength of the refractory material, in particular of the top element, which is designed as a carrier upon two supports. On the other hand, substantial thermal expansions of the substructure are encountered during continuous operation and alter the clear cross section of the casting nozzle in an undesired manner. Also the production of very broad casting nozzles of refractory material drives up costs in a way that is no long justifiable.